Isolation and characterization of two canine melanoma cell lines: new models for comparative oncology

Abstract

BackgroundMetastatic melanoma is one of the most aggressive forms of cancer in humans. Among its types, mucosal melanomas represent one of the most highly metastatic and aggressive forms, with a very poor prognosis. Because they are rare in Caucasian individuals, unlike cutaneous melanomas, there has been fewer epidemiological, clinical and genetic evaluation of mucosal melanomas. Moreover, the lack of predictive models fully reproducing the pathogenesis and molecular alterations of mucosal melanoma makes its treatment challenging. Interestingly, dogs are frequently affected by melanomas of the oral cavity that are characterized, as their human counterparts, by focal infiltration, recurrence, and metastasis to regional lymph nodes, lungs and other organs. In dogs, some particular breeds are at high risk, suggesting a specific genetic background and strong genetic drivers. Altogether, the striking homologies in clinical presentation, histopathological features, and overall biology between human and canine mucosal melanomas make dogs invaluable natural models with which to investigate tumor development, including tumor ætiology, and develop tailored treatments.MethodsWe developed and characterized two canine oral melanoma cell lines from tumors isolated from dog patients with distinct clinical profiles; with and without lung metastases. The cells were characterized using immunohistochemistry, pharmacology and genetic studies.ResultsWe have developed and immunohistochemically, genetically, and pharmacologically characterized. Two cell lines (Ocr_OCMM1X & Ocr_OCMM2X) were produced through mouse xenografts originating from two clinically contrasting melanomas of the oral cavity. Their exhaustive characterization showed two distinct biological and genetic profiles that are potentially linked to the stage of malignancy at the time of diagnosis and sample collection of each melanoma case. These cell lines thus constitute relevant tools with which to perform genetic and drug screening analyses for a better understanding of mucosal melanomas in dogs and humans.ConclusionsThe aim of this study was to establish and characterize xenograft-derived canine melanoma cell lines with different morphologies, genetic features and pharmacological sensitivities that constitute good predictive models for comparative oncology. These cell lines are relevant tools to advance the use of canine mucosal melanomas as natural models for the benefit of both veterinary and human medicine.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-5114-y) contains supplementary material, which is available to authorized users.

Cross-species analysis of enhancer logic using deep learning

“…Predicting enhancers and determining their functional role within gene regulatory networks has been an active field for years. Despite the well-established power of cross-species approaches in this field, to our knowledge, a large comparative epigenomics study in melanoma has not yet been conducted, although several non-human models are commonly used in melanoma research (van der Weyden et al 2016) and have been studied on an intra-species level (Hitte et al 2019;Jiang et al 2014;Kaufman et al 2016;Rambow et al 2008;Rosengren Pielberg et al 2008;Seltenhammer et al 2014;Sundström et al 2012) or in relation to human melanoma (Egidy et al 2008;Segaoula et al 2018;Rahman et al 2019). Here, we demonstrate that the MEL and MES states are conserved across species, as well as the key regulators of these states.…”

“…However, it remains unclear how these regulatory states are encoded in particular enhancer architectures, and whether such architectures are evolutionary conserved. Besides human cell lines and human patient-derived cultures, several animal models have been established in melanoma research, including mouse, pig, horse, dog and zebrafish (Egidy et al 2008;van Rooijen et al 2017;Segaoula et al 2018;Seltenhammer et al 2014;van der Weyden et al 2016;Prouteau and André 2019). Although these models are widely used, it is unknown whether their enhancer landscapes and regulatory programs are conserved with human.…”

Aggressiveness Potential of Spontaneous Canine Mucosal Melanoma Can Dictate Distinct Cancer Stem Cell Compartment Behaviors in Regard to Their Initial Size and Expansion Abilities

“…Two canine melanoma cell lines, OCR_OCMM1 and OCR_OCMM2, were isolated from melanoma tumor tissues obtained from a 14-year-old Yorkshire Terrier and an 11-year-old German Shepherd, respectively, that presented melanocytic lesions of the oral cavity, as previously described [ 11 ]; only the latter dog had metastasis to the lungs. The storage and use of canine biological samples were declared and were performed according to ethical rules approved by the Department of Health, France.…”

“…Population doubling times (PDTs) were evaluated for each cell line in adherent and spheroid conditions. Cells were plated at a density of 1 × 10 5 cells in 60-mm petri dishes with 4 mL of complete growth medium and were then incubated at 37°C in a controlled-humidity atmosphere with 5% CO 2 for 96 h. Cells were trypsinized (0.25% EDTA) and counted every day in duplicate, and the PDT was calculated using the following formula: PDT = 1/[3.32(logNH − logNI)/(t2 − t1)] (where t1 = time in hours when cells were seeded; t2 = time in hours when cells were harvested; NI = cell count when cells were seeded; and NH = cell count when cells were harvested), as previously described [ 11 ].…”

“…In humans, mucosal melanoma of the oral cavity is rare but is highly aggressive and metastatic [ 9 ], with frequent relapse and poor outcomes [ 10 ]. Recently, we isolated and characterized two canine oral melanoma cell lines (OCR_OCMM1 and OCR_OCMM2) from spontaneous mucosal melanoma tumors from canine patients with distinct clinical profiles and metastasis patterns [ 11 ]. The OCR_OCMM1 and OCR_OCMM2 melanoma cell lines had similar morphological, histological, and DNA copy number alteration (CNA) features to the original tumor and showed similar resistance/sensitivity to current antimelanoma drugs that are used for humans, suggesting the relevance of these cell lines as powerful research tools for human and canine medicine [ 11 ].…”